CODEWITHSUNDEEP
kotlinmicronaut
hangry horse
hangry horse

Reputation: 87

How can I use environment specific variables in micronaut?

I'm new to micronaut and server side programming in general. The micronaut documentation, unfortunately, does not make a lot of sense to me, as I do not have a Java background. A lot of the terms like "ApplicationContext" make sense in english, but I have no idea how to use them in practice.

Trying to start with a very basic app that prints different configurations ("localhost", "dev", "prod") depending on the environment it is in.

Here's my controller

@Controller("/")
class EnvironmentController {

    // this should return "localhost", "DEV", "PROD" depending on the environment
    @Get("/env")
    @Produces(MediaType.TEXT_PLAIN)
    fun env() = "???" // what should I put here ?

    // this should return the correct mongodb connection string for the environment
    @Get("/mongo")
    @Produces(MediaType.TEXT_PLAIN)
    fun mongo() = "???" // what should I put here ?
}

Here's the application.yml. Ideally I'd have 1 yml file for each environment

micronaut:
  application:
    name: myApp
  server:
    port: 8090

environment: localhost

mongodb:
  uri: 'mongodb://localhost:27017'

Application.kt is untouched with the rest of the files generated by the mn cli tool. How can I set per environment parameters, or pass the yml file as a parameter when starting micronaut?

Are there any conventions around this?

Upvotes: 5

Views: 25705

Answers (3)

Jan Bodnar
Jan Bodnar

Reputation: 11657

To be able to use environment specific variables in controllers and other classes., we have to inject them into fields.

Property values can be loaded with the @Value, @Property or @ConfigurationProperties annotations.

@Property(name='app.message', defaultValue = 'unknown')    
private String message

@Property(name='env.test', defaultValue = 'env.test not set')
private String envt

@Property(name='env.dev', defaultValue = 'env.dev not set')
private String envd

Assuming that app.message is defined in both dev and test environments, it is loaded from the property source that is defined last. (For instance, in MICRONAUT_ENVIRONMENTS=dev,test test is defined last and takes precedence.)

If env.test is defined in the test environment, it is loaded from the application-test.properties property source. Likewise, the env.dev is loaded from application-dev.properties.

Also note that the default environment set by the application builder's defaultEnvironments method is only applied when no other active environments are detected. Otherwise, the default environment is ignored.

Upvotes: 0

San Jaisy
San Jaisy

Reputation: 17118

By default Micronaut only looks for application.yml. Then, for tests,dev and prod, it loads application.yml and overrides any values there with the ones defined in application-test.yml, application-dev.yml and application-prod.yml If you want to enable any other environment, you need to do it manually

public static void main(String[] args) {
    Micronaut.build(args)
             .mainClass(Application.class)
             .defaultEnvironments("dev")
             .start();
}

https://docs.micronaut.io/latest/guide/index.html#_default_environment

Upvotes: 3

James Kleeh
James Kleeh

Reputation: 12228

You can specify an environment with -Dmicronaut.environments, or by specifying them in the context builder Micronaut.run in your Application class.

https://docs.micronaut.io/latest/guide/index.html#environments

Then for example application-env.yml will be loaded.

https://docs.micronaut.io/latest/guide/index.html#propertySource

The docs are pretty clear on this

Upvotes: 10

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